Combined acetonitrile and aromatic hydrocarbon solvent solution of a vinyl chloride-vinyl acetate copolymer



COMBINED ACETONITRILE AND AROMATIC HY- DROCARBON SSLVENT SOLUTION OF A VINYL CERORIDE-VHNYL ACETATE COPGLYMER Gerald P. Roeser, Fallsington, Pa., assignor, by mesne assignments, to American-Marietta Company, Stoner- Mudge Co. Division, Chicago, 111., a corporation of Illinois No Drawing. Application February 9, 1956 Serial No. 564,376

Claims. (Cl. 26032.4)

This invention relates to the use of acetonitrile in conjunction with aromatic hydrocarbon solvents to dissolve certain resins, especially copolymers of vinyl chloride and vinyl acetate.

Vinyl polymers and copolymers have become well known in many industries for their valuable properties, and one phase of their development has been a search for suitable solvents to form solutions of the polymers for various purposes, such as protective coatings, films, and various other plastic applications. There are a number of active solvents which have been found to be generally suitable for such purposes, such as isophorone, cyclohexanone and methyl ethyl ketone. Such active solvents are expensive, however, and consequently attempts have been made to find less expensive substitutes. The

common aromatic hydrocarbon solvents are much lessexpensive, but they can be used only as diluents with more active solvents to dissolve most vinyl polymers and copolymers, with rare exceptions; e. g., straight aromatic hydrocarbon solvents with vinyl chloride/vinylidene chloride copolymers as disclosed in Gray and Reymann U. S- Patent 2,675,334. In the case of copolymers of vinyl chloride and vinyl acetate, which are among the most widely accepted and useful of the vinyl compounds, particularly in the protective coating field, it is necessary touse expensive active solvents, either exclusively or in relatively large proportions with aromatic hydrocarbon solvents, in order to dissolve the vinyl chloride/vinyl acetate copolymers sufiiciently to obtain the desired viscosity. The resultant expense and other difficulties have led to a long continued search for other solvent materials which could be used in smaller proportions with aromatic hydrocarbon' solvents for obtaining suitable solutions of vinyl chloride/vinyl acetate copolymers.

I have discovered that there is a synergistic relation between acetonitrile (CH CN) and liquid aromatic hydrocarbons such as benzene, toluene and xylene, and mix- 1 tures thereof, whereby the combination of the two is highly effective when used with certain resins, particularly copolymers of vinyl chloride and vinyl acetate containing less than 90% by weight of vinyl chloride. There is evidently a special relation between the acetonitrile component of the solvent system and the aromatic hydrocarbon component, because neither one of the components used alone is capable of dissolving these resins, but the combination of the two components is highly effective in dissolving them. The combination is particularly valuable because of its usefulness as a solvent for vinyl chloride/ vinyl acetate copolymers, which are of major commercial importance, and because a very high percentage of the aromatic hydrocarbon component, which is relatively inexpensive, can be used in the solvent mixture for purposes of dissolving vinyl chloride/vinyl acetate copolymers, in spite of the fact that such copolymers are noted for their resistance to dissolution in conventional solvent mixtures 2 containing like percentages of such aromatic hydrocarbon component.

The solvent composition of the invention consists of the combination of acetonitrile with benzene, toluene or xylene, or mixtures thereof. Xylen'e is' less effective in the combination than either benzene or toluene, and where xylene is present the minimum effective proportion of acetonitrile increases slightly, but the maximum effective proportion remains the same. Toluene is preferred because it has the best solvent action in conjunction with acetonitrile, and because it does not have the toxic characteristics of benzene. When used as a solvent for copolymers ofvinyl chloride and vinyl acetate containing about 87% by weight of vinyl chloride, the composition of the invention is effective in a range of proportions by weight of acetonitrile (the balance being benzene, toluene or xylene, or mixtures thereof) between and including a maximum of substantially 65%, and a minimum of substantially 5% plus, only in the case when xylene is present, an additional 2.5% multiplied by a factor equal to the weight of the xylene divided by the total weight of (1) xylene, or (2) benzene and xylene, or (3) benzene and toluene, or (4) benzene, toluene and xylene, as the case may-be, which are present in the combination. As the proportion of vinyl chloride in the copolymer is decreased below 87% the greater solvency of the vinyl acetate in the copolymer makes the composition of the invention etfective as a solvent for the copolymer with a progressively smaller minimum and larger maximum proportion of acetonitrile.

The following Table I shows the effectiveness of acetonitrile as compared with methyl ethyl ketone and tetrahydrofuran when used in various proportions with toluene, in terms of viscosities (in seconds at F. with #4 Ford cup) of compositions consisting of' uniform samples of vinyl chloride/vinyl acetate copolymer (87/ 13 ratio, VYHH) at 18% solids by weight in the various solvent mixtures (component ratios by weight):

Table I.C0mparative viscosities [Seconds at 80 F. with a #4 Ford cup] Solvent Combination Ratio of components in solvent (1) (methyl (2) (tetrahy- (3) (acetoniethyl ketone drofuran and trile and and toluene) toluene) toluene) Swollen.

Do. Do. Do. 27. 25. 23. 22. 22. 24. 29. 34. 43. 47. 65. 0....;... G61. do Do.

It is particularly significant to note in the above Table I that when the solvent mixture hasmore than 50% toluene in the solvent mixture, acetonitrile is far more effective in the solvent mixture than conventional strong solvents such as methyl ethyl ketone and tetrahydrofuran. p

The following Table -II shows the effect ofusing various aromatic hydrocarbon components in various proportions with acetonitrile, in terms of viscosity (in'seconds 7 a, $2,865,879 r 3 a 4 at 80 F. with #4 Ford cup) of compositions consisting easily dissolved. For example, 100% vinyl acetate of uniform samples of vinyl chloride/vinyl acetate co polymer dissolves in 100% toluene, and in any mixture polymer (87/13 ratio, VYHI-I) at 18% solids by weight of toluene with acetonitrile containing not more than in the various solvent mixtures: 95% acetonitrile.

[Seconds at 80 F. with a #4 Ford cup] Ratio of acetonitrile to the Solvent; combination of acetonitrile witharomatic hydrocarbon specified in adjacent headings (by weight) Benzene Toluene Xylene Solvesso Solvesso 100/0 Swollen." Swollen. Swollen. Swlolleu. Swollen. r.

In the above Table H, Solvesso #100 and Solvesso Compositions employing the polymer and solvent com- #l50 are commercial mixed aromatic hydrocarbon bination of the invention are useful for protective coatsolvents. When commercial naphthene spirits, such as ing and other purposes for which vinyl chloride/vinyl Troluoil and Apco Thinner, or aliphatic hydrocaracetate solutions are used. For example, a composition bons, such as Stodso, are used with acetonitrile in of the above-described VYI-IH" vinyl chloride/vinyl aceany proportions as a solvent for the same copolymer, tate copolymer at 21% applied solids in solvent consistthe results are total insolubility or close to it. ing of 67% toluene and 33% acetonitrile was filmed on The following Table III shows the efiectiveness of tinplate at 4.7 m. g./sq. in and baked thereon at 325 F. acctonitrile and toluene with various kinds of vinyl for ten minutes. The coating was tested for color, clarity, resins, in terms of comparative viscosities (in seconds flow, adhesion, insolubil y, flexibility, after pasteuriat 80 F. with #4 Ford cup) when using acetonitrile 35 zation at 170 F. for minutes, for blush, blistering, and toluene separately and in various combined proporp i g and Wet adhesion For P p of Comparison, tions, with the resins: a composition of the same copolymer at 19.5% applied solids in solvent consisting of 67% toluene and 33% Table [IL-Comparative viscosities with difierent resins methyl ethyl ktone was filmed 011 like SPBCimEIIS at 5.3 mg./ sq. in. and then baked and tested as stated above.

The results were the same in both cases, showing that t h 4 coating qualities are not adversely affected by substitution Re in 5;; Rat-10 acetonrtr1le/toluene(by weight) or acetonitrile for such standard solvents as methyl Total ethyl ketone in coating compositions of vinyl chloride/ Sohds 100/0 65/35 /50 5/95 0/100 45 vinyl acetate .copolymers. The composition of the invention can have a viscosity range of 20 to 150 seconds [Seconds at 80 F. wt-ih a #4 Ford cup] VYHH l8 InsoL- 27 22 65 Insol.

20 90 lump in #4 Ford cup at 80 F., and a solids concentration of ,;k lg Gel gg vinyl ChIOIId B/VIDYI acetate copolymer of up to about VYNS 15 I nsol Swollen.-. Gel. was Insol. y e gh for m Protect!e coalmg P p W 50 but these ranges can be exceeded for some protective coating purposes. slll pl mq ll llg h ll-1. Tabl the si y I Pigments, dyes, waxes and other non-reactants may be ings for VMC are 34 and 39 nds at a n l added to the composition of the invention for decorative 1501116116 ratio of 20/80 and 10/90, respectively, and purposes and the like, without otherwise materially affect- VAGH are 43, 37, 40, 44 and 71 seconds at acetonitrile/ ing the significant characteristics of the composition. toluene ratios of 615/385, 25/75, 20/30 While I have described present preferred embodiments and 15/85, respectively; of the invention and methods of practicing the same, it

In the above Table III, VYI-IH and VYLF are cowill be recognized that the invention is not limited therepolymers of vinyl chloride and vinyl acetate in proporto but may be otherwise variously embodied and practions of 87/ 13 by weight, the difierence between the two ,0 ticed within the scope of the following claims. lying in the fact that VYHH has a higher molecular i claim: weight, VMCH is a copolymer of vinyl chloride, vinyl 1. A resin composition comprising a copolymer of acetate and maleic anhydride, in proportions by weight of vinyl chloride and vinyl acetate containing a major pro- 86/ 13/ 1. VAGH is a partially hydrolyzed copolymer portion by weight or" vinyl chloride, said copolymer being of vinyl chloride and vinyl acetate, the copolymer being ,5 dissolved in a solvent composition consisting essentially originally like VYHH, but changed by hydrolysis to of acetonitrile and liquid aromatic hydrocarbon solvent, proportions by weight of 6% vinyl alcohol, 3% vinyl said acetonitrile being present in said mixture of acetoacetate and 91% vinyl chloride. VYNS is a copolynitrile and liquid aromatic hydrocarbon solvent in pro mer of vinyl chloride and vinyl acetate in proportions portions of from substantially 5% to by weight. by weight of 90/ 10. 2. A resin composition as recited in claim 1 in which The mixed solvent of the invention is effective with the proportion of vinyl chloride in said copolymcr comcopolymers of vinyl chloride and vinyl acetate containing prising vinyl chloride and vinyl acetate is about 87% by less than 90% by weight of vinyl chloride. There is no weight.

upper limit on the amount of vinyl acetate in the copoly- 3. A resin composition as recited in claim 2 in which mer because the vinyl acetate component is relatively said liquid aromatic hydrocarbon solvent includes a proportion of xylene and said acetonitrile solvent is present in said mixture of liquid aromatic hydrocarbon solvent and acetonitrile in a minimum proportion by weight of substantially 5%, plus 2.5% multiplied by a fraction equal to the weight of xylene present, divided by the total weight of liquid aromatic hydrocarbon solvent, the maximum proportion of said acetonitrile solvent in said mixture of liquid aromatic hydrocarbon solvent and acetonitrile being 65% by weight.

4. A resin composition as recited in claim 2 in which said liquid aromatic hydrocarbon solvent is selected from the group consisting of benzene, toluene, xylene and mixtures thereof, the minimum proportion of saidacetonitrile component by weight based on the total weight of liquid aromatic hydrocarbon solvent and acetonitrile being substantially 5% plus 2.5% multiplied by a fraction equal to the weight of xylene present, divided by the total weight of liquid aromatic hydrocarbon solvent, the maximum proportion of said acetonitrile solvent in said mixture of liquid aromatic hydrocarbon solvent -an'd acetonitrile being 65% by weight.

5.'A resin composition comprising a copolymer of vinyl chloride and vinyl acetate containing about 87% by weight of vinyl chloride, said copolymer being dissolved in a solvent composition consisting essentially of acetonitrile and toluene, said acetonitrile being present in said mixture of acetonitrile and toluene in proportions of from substantially 5% to 65 by weight. a

6. A resin composition as recited in claim 5 in which the percentage of acetonitrile is substantially 5%.

7. A resin composition comprising a copolymer of vinyl chloride and vinyl acetate containing about 87% by weight of vinyl chloride, said copolymer being dissolved in a solvent composition consisting essentially of acetonitrile and benzene, said acetonitrile being present in said mixture of acetonitrile and benzene in proportions of from substantially 5% to 65% by weight.

8. A resin composition as recited in claim 7 in which the percentage of acetonitrile is substantially 5%.

9. A resin composition comprising a copolymer of vinyl chloride and vinyl acetate containing about 87% by weight of vinyl chloride, said copolymer being dis.-

solved in a solvent composition consisting essentially of acetonitrile and xylene, said acetonitrile being present vin said mixture of acetonitrile and xylene in proportions 'of from substantially 7.5% to 65 by weight.

10. A resin composition as recited in claim 9 in which the percentage of acetonitrile is substantially 7.5%.

References Cited in the file of this patent UNITED STATES PATENTS 2,706,185 Kowolik et a1. Apr. 12, 19 

1. A RESIN COMPOSITION COMPRISING A COPOLYMER OF VINYL CHLORIDE AND VINYL ACETATE CONTAINING A MAJOR PROPORTION BY WEIGHT OF VINYL CHLORIDE, SAID COPOLYMER BEING DISSOLVED IN A SOLVENT COMPOSITION CONSISTING ESSENTIALLY OF ACETONITRILE AND LIQUID AROMATIC HYDROCARBON SOLVENT, SAID ACETONITRILE BEING PRESENT IN SAID MIXTURE OF ACETONITRILE AND LIQUID AROMATIC HYDROCARBON SOLVENT IN PROPORTIONS OF FROM SUBSTANTIALLY 5% TO 65% BY WEIGHT. 